Lime mortar and plaster



j f Patented' F eh- 12193 I A a i LIMEMORTAR AND PLASTER' Leroy C.Stewart,"Midland, Mich, assignor to The Dow Chemical Company, Midland,Mich., a corporation of Michigan; 9 e No mapwi'ng. .fApplicationMarch16, 51931,

, ,Se'rial N0.:523,193 I s Claims. (01. 196524) The subject matter ofthe present invention is umes of sand," is preferably intimately mixedconcerned with lime mortars and'plasters, espe-, infltheusualmanner-withfromg4to ZO'percent cially with a method of improving the strength, ofmagnesium chloride (MgC12.6H2O) or magnesi-Q durabili y and otherproperties of'such materials, um'sulphate (MgSOiflI -Iz'O) based on .theWeight. )5 as 'well as with the; improved product prepared ofthehydrated lime, and from 1% to 3 percent," 5

thereby. 1 j I J v, o based on "the, weight of MgClzfiI-IzO and/or-Materials of the above type, when prepared and" MgfiOn'YI-IzOQ of acompound or mixture of 'com-- applied in the usual manner, are oftendeficient in pounds from the group hereinbefore' indicated, strength andtherefore. break or crack when sub consisting of phosphoric, citric, andtartaric acid 10 .jected to even small stresses, thus much weaken-,andthe alkali metaland ammonium salts thereof; 0 ing the joints orwalls, etc. on which employed ,The abovemixture is then mixedwith waterto a and-necessitating costly and-troublesome repairs. trowelingconsistency. Y i 1 1 To improve these materials, ithas beenproposed f Todetermine the improvement in mortars due to mix Portland cementtherewith, but the large to'the additive ingredients, mixtures were made1 amount required, howevenhas made such use of upas aforesaid and formedinto standard j 55 out external. physical support, and about 3 v l,

little advantage. For. instance, as muchasi25 briquets, aged'and testedas hereinafter indicated.- per cent of cement in proportion .to theweight Inthe {following examples, which are given for of [lime isrequired: to give even a noticeable the purpose of illustration,theftensile strength increase of strength in a rich'lime mortar; and invalues'ior the various periods of time are shown 39, ,aleanmortane. g.one containing lime hydrate and expressed in pounds persquare inch, andare and sand-infthe proportion by volume of about 'theaverage of thevalues obtained in each in- -1 to 3, sometimes as much as 50 per centof'cem'ent' stance from th a, sp h limes mto the weight of lime isnecessarytoefiect an'aplployed in the following exa p Were Commercialpreciable increase instrength. It hasbeen fur hydrated lime 'or quicklime ma p vWith W r .2 ther proposed to mix certain soluble salts, suchas t0 the co s s y of p y, m i'rOin a differmagnesiumchloride ormagnesium sulphate, in em source b 'usd inea X D 100varying'percentages,.e. g. from 2 to 20 per cent or pounds of suchhydrated lime wasadded 16 more, with such .lime mortars, and distinctlypounds of MgC12.6I-I2O and the given-weight of beneficial-effects aresaid to have resulted there t b n fi ing compoundj The latter two mate-'from, particularly in increase in strength, durrials had been finelypulverized together into a 30 ability, and workability.substantially"homogeneous mixture previous to.

I I have now found that still furtherbeneficial adding to the putty.With the gradual addition results may be obtained in such-solublesalt-lime of water to the. materials, 'the same were then, mortarand-plaster mixtures containing magnesia stirred to a-trowelingconsistence and made up um chloride by intimately mixing therewithalintobriquets VIII The following examplesthe small-amount of a compoundincluded withinthe' cent of", magnesium, chloride, MgClzfiHzO, k is]group consisting of citric, phosphoric and tartaric "basedupon theweight'ofhydratedlime used, and

acidsand thealkali-metal a'ndammonium salts-the percent of beneficialsubstance; e. gl citric of such acids. To. the accomplishment 'of-theacid, disodium phosphate or tartaric acid, is based 0 foregoing and.related ends, the invention, then. upon the weight of magnesiumchloride. consists of the features hereinafter fully described 7 andparticularly pointed out in thercla'ims, the k A LE Ifollowingrdescription setting ,forth, in detail v v a e I v I severalpreferred combinations-of ingredientsand Hydrated lime containingmagnesium chloride,

modes ofparrying out the invention, such dis- I (MgCZzfiHrO) andc'itricacid.

closed;combinations' and modes constituting, I

however, but several of -various ways ln which the. Test i' A B I d. DfE princ ple of theinvention may be usedr I. In efiectingmy io .lime m tMgClaGHaOpercentnnnl;None 1e "16 1 16 "-16 16' 50 plaster-containing 1volume of lime putty, eg. g t i ac E y-, e I g a lime hydrate made up tosuch a consistency r i ifi sg? iii-f;'h?l f 1Z- 1&1, 5 3 with water an-stirrjno' 7-daytensile strength 8 20 20 21 22 18 l d 1 d a 30-daytensile strength 15 43 53 57 57 43 w1l1 substantially mamtam a-givenposition w th- 90-day tensilestrength 21 84 85 143 147. v 126 EXAMPLE IIHydrated lime containing magnesium chloride (M gCZ2.6HzO) and disodiumphosphate EXAMPLE III Hydrated lime containing magnesium chloride(MgCZzfiHnO) and tartaric acid Test specimen A B O D E F MgCl26I-[2O percent; 16 16 16 16 Tartaric acid per cent 0. 5 1 2 3 Initial set (hr.;min.) 6:00 6:00 Final set (hr; min.) l 18:00 18:00 18:00 7-day tensilestrength"; 6 14 23 22 26 16 30-day tensile strength 8 50 61 57 62 4990-day tensile strength 10 102 114 153 144 112 Although the significanceof the data givenirr the foregoing examples is apparent, yet certainoutstanding features of my invention may be noted. I y p In specimen Aof each such example resultsof tests on lime mortarsalone are given, thesame showing the rather wide range of strength that might beordinarilyexpected in such materials when used for the purpose inquestion. In like manner in specimen B, such limes are mixed withmagnesium chloride (MgC12.6H2O) to illustrate the beneficial effect ofadding such chloride separately thereto. Still further, the results setforth in specimens 0, D, E, and F, respectively, show the additionalbeneficial effects obtained in such;

mixture asemployed in specimen B, when small amounts of the beneficialcompounds are used according to the invention, such beneficial. effectsbeing particularly outstanding in the tensile strengths shown for thelonger periods of time, for instance, in test specimens D and E ofExamples I and III, respectively, and in test specimens E and'F, ofExample II. The results obtained with different limes may also varyconsiderably in agiven series of'tests; however, practically all limemortars and plasters when treated according to my invention were foundto be greatly benefited, in some instances an increased strength offive; to seven-hundred per cent or more being obtained compared with theorig 'inal lime plaster and an additionalincreased strength oftwenty toseventy-five per cent. over that of the composition consisting of suchlime and the magnesium chloride (MgClzfiHzO) and/ or magnesium sulphate(MgSOa'iI-Iz-O) alone.

The percentage of magnesium chloride (MgCIaGI-IZO) used is thesarne inall examples, 1. e. 16, per cent, and is thus employed forconveniencein'the interpretation of the results obtained. However, smallerquantities of the magnesium chlorida'as little as 2 per cent even, orlarger amounts, as much as 30 percent ormore, have given verysatisfactory results.

By the term; lime of lime mortars and plasters, asused in, thespecification, is meant either calcium hydrate or. calcium-magnesiumhydrate,

, such hydrates being obtained by decarbonating It is also noted thatthe thin finishing lime mortar coating for walls, for instance, may belikewise benefited by treating according to my invention. In suchinstance, however, in place of a putty being made up and applied by atrowel, a thick lime hydrate suspension, with or without a. sand orother suitable fillcr,-as desired,:is preferably providedand an aqueoussolution of a given strength of the soluble magnesium salt and thebeneficial compound, as previously indicated, intimately mixed therewithand the same applied with a brush or in other suitable manner. The

lime coating thus made forms a better bond with the surface upon whichit is applied, and, in drying, checks and breaks less and may be appliedmore easily than that previously used for such I v purpose.

It is obvious that when acids such as citric and tartaric acid are mixedwith lime mortars that the lime salt of the corresponding acid is formedand is the active beneficial principle. In a general way both the acidsand salts included Within the group of nitrates, phosphates,andtartrates are applicable to the invention; The action of thematerials forming the basis of my invention is not well known, but it isbelieved that such beneficial materialsexert a dispersing effect'on themixture of lime and mag'nesiumchloride, magnesium sulphate, or themagnesium hydrate formed in the reaction, thus producing an increaseinfstrengthjhardness and otherwise benefiting such mortars and plasters,The mortar compositions thus'provide'd are also more plastic and may beworked with greater facility.

'In certain instances where a less hygroscopic mortar. is'desired, I maymix with the limehydrate a mixtureof magnesium chloride and magnesiumsulphate. Mixtures of two or. more of the active ingredients comprisingmy invention such as the citrates, phosphates, etc. may be made upbeforehand or mixed in the mortar. For

, facilitating shippingand' handling, the. magnesiumchloride' andthecitrate, phosphate or tartrate are preferably mixed in dryiorm, suchmixture being suitable for incorporating in the mortar or plasterpractically asused commercially. The .method of adding the citric acid,disodium phosphate, etc. is a matter of convenience-only and may beaccomplished in any suitable manner. In summation, my inventionconsistsin adding certain beneficial substances to lime mortars and plasterscontaining varying amounts of soluble magnesiumsalts such a magnesiumchloride, for instance,-whereby, when such mixtures are admixed withwater, they set up to form materials of the type in question whichpossess increased strength, greater density and durability and areotherwise of superior quality. The invention also includes the improvedproducts made according to'the method disclosed.

Other modes of applying the principle of my invention may be employedinstead of the one explained, change being made as regards-the stated byany of the following claims or the equivalent of such stated ingredientsbe employed.

I therefore particularly point out and distinctly claim as my invention:

'1. A method of improving lime mortars and plasters which comprisesintimately mixing therewith about 4 to 30 per cent of magnesiumchloride,.based upon theweight of the lime, and to 3 percent of citricacid based upon the 1/; to 3 per cent of citric, acid based upon theweight of'magnesium chloride (MgClaGI-IzO);

. 2. Anew lime'mortar and plaster composition comprising a mixture ofhydrated lime to which has been added magnesium chloride together with arelatively small amount of citric acid intimately mixed therewith, saidcomposition being" adapted to setting up when admixed with water.

3. A new lime mortar and plaster composition 4. A lime mortar andplaster composition comprising hydrated lime to which has been addedfrom 4 to 30 per" centof magnesium chloride, MgClz.6HzO, together withfrom 0.5 to 3 per cent, based upon the weight of magnesium chloride, ofacompound from the group consisting of phosphoric acid and thealkali-metal and ammonium'phosphates, said composition being adapted toset when admixed with water.

5. A method of improving 'limemortars and plasters which comprisesintimately mixing therewith from 4 to 30 per cent by weight of a solublemagnesium salt, based upon the weight of the lime, and from to 3 percent by weight, based upon the weight of the magnesium salt, of acompound selected from the group consist- ,plasters which comprises ingof citric, phosphoric and tartaric acids and the alkali-metal andammonium salts of such.

.acids.

6. A method of improying lime mortars intimately 'mixing therewith fromA: t0' 30 per cent by weight of magnesium chloride, MgClzfiHzO, basedupon theweight of the lime,,and from to 3 per cent by Weight-based ,uponthe weight of the, mag

nesium chloride, ofa compound selected'from the group consisting ofcitric, phosphoric and tartaric acids and the alkali-metal and am moniumsalts of such acids.

7. A lime mortar and plaster composition comprising hydrated lime towhich has been added fromlto 30 per cent of itsweight of a solublemagnesium salt, and from /2 to 3 per cent by, weight, based upon therweight; of the magnesium salt, of a compoundselected from the groupconsisting of citric, phosphoricvand tartaric acids and the alkali-metaland ammoniumsalts of such acids. j

8. A lime mortar and plaster composition comprising hydrated lime towhich has been added from 4 to 30 per cent of its weight of magnesiumchloride, MgC12.6H2O, and from 00.3 per cent by weight, based upon theweightof the magnesium chloride, of a compound selected from the groupconsisting of citric, phosphoric and tartaric acids-and the alkali-metaland ammonium salts of such acids.

. LEROY C. STEWART

